Anatomi mammae

The breasts of an adult woman are milk-producing, tear-shaped glands. They are supported by and attached to the front of the chest wall on either side of the breast bone or sternum by ligaments. They rest on the major chest muscle, the pectoralis major.

The breast has no muscle tissue. A layer of fat surrounds the glands and extends throughout the breast.

The breast is responsive to a complex interplay of hormones that cause the tissue to develop, enlarge and produce milk. The three major hormones affecting the breast are estrogen, progesterone and prolactin, which cause glandular tissue in the breast and the uterus to change during the menstrual cycle.

Each breast contains 15 to 20 lobes arranged in a circular fashion. The fat (subcutaneous adipose tissue) that covers the lobes gives the breast its size and shape. Each lobe is comprised of many lobules, at the end of which are tiny bulb like glands, or sacs, where milk is produced in response to hormonal signals.

Ducts connect the lobes, lobules, and glands in nursing mothers. These ducts deliver milk to openings in the nipple. The areola is the darker-pigmented area around the nipple.

More information about breast anatomy is provided in the following two graphic figures:

Figure 1: Quadrants of the Breast Figure 2: Regional Lymph Nodes of the Breast

Figure 2: Quadrants of the Breast

Note: C50.6 is the code for axillary tail or tail of breast.

 Blood and lymph vessels form a network throughout each breast. Breast tissue is drained by lymphatic vessels that lead to axillary nodes (whichlie in the axilla) and internal mammary nodes (which lie along each side of the breast bone). When breast cancer spreads, it is frequently to these nodes.

2. Axillary lymphatic plexus 7. Brachial axillary lymph nodes

4. Cubital lymph nodes *8. Interpectoral axillary lymph nodes (Rotter nodes)

5. Superficial axillary (low axillary) 10. Paramammary or intramammary lymph nodes

6. Deep axillary lymph nodes11. Parasternal lymph nodes (internal mammary nodes)

* Note: the cubital lymph nodes are not part of the lymph node drainage of the breast.

Sentinel nodes — Click here.

Image - Breast Anatomy (http://www.breastcancer.org/pictures/breast_anatomy/image_1.jsp)

Breast profile:

A ducts

B lobules

C dilated section of duct to hold milk

D nipple

E fat

F pectoralis major muscle

G chest wall/rib cage

Enlargement:

A normal duct cells

B basement membrane

C lumen (center of duct)

Find out where and how different cancer types affect the breast.

Image - Axillary Lymph Nodes

Lymph node areas adjacent to breast area.

A pectoralis major muscle

B axillary lymph nodes: levels I

C axillary lymph nodes: levels II

D axillary lymph nodes: levels III

E supraclavicular lymph nodes

F internal mammary lymph nodes

Read more about axillary lymph nodes and their role in diagnosing and treating breast cancer.

Breast Anatomy and Physiology Format for Printing

It is important for women to become familiar with the normal anatomy and physiology (function) of their breasts so that they can recognize early signs of possible abnormalities. This section outlines basic information on breast composition, development, and typical changes from puberty to pregnancy to menopause.

Main Menu:

Breast Composition Initial Breast Development Breast Size, Appearance, and Changes Over Time Breast Changes During Pregnancy Breast Changes After Menopause Additional Resources and References

Breast Composition

The breast is a mass of glandular, fatty, and fibrous tissues positioned over the pectoral muscles of the chest wall and attached to the chest wall by fibrous strands called Cooper’s ligaments. A layer of fatty tissue surrounds the breast glands and extends throughout the breast. The fatty tissue gives the breast a soft consistency.

Image courtesy of NCI/NIH

The glandular tissues of the breast house the lobules (milk producing glands at the ends of the lobes) and the ducts (milk passages). Toward the nipple, each duct widens to form a sac (ampulla). During lactation, the bulbs on the ends of the lobules produce milk. Once milk is produced, it is transferred through the ducts to the nipple.

The breast is composed of:

milk glands (lobules) that produce milk ducts that transport milk from the milk glands (lobules) to the nipple nipple areola (pink or brown pigmented region surrounding the nipple)

connective (fibrous) tissue that surrounds the lobules and ducts fat

Arteries carry oxygen rich blood from the heart to the chest wall and the breasts and veins take de-oxygenated blood back to the heart. The axillary artery extends from the armpit and supplies the outer half of the breast with blood; the internal mammary artery extends down from neck and supplies the inner portion of the breast.

Initial Breast Development

Human breast tissue begins to develop in the sixth week of fetal life. Breast tissue initially develops along the lines of the armpits and extends to the groin (this is called the milk ridge). By the ninth week of fetal life, it regresses (goes back) to the chest area, leaving two breast buds on the upper half of the chest. In females, columns of cells grow inward from each breast bud, becoming separate sweat glands with ducts leading to the nipple. Both male and female infants have very small breasts and actually experience some nipple discharge during the first few days after birth.

Female breasts do not begin growing until puberty—the period in life when the body undergoes a variety of changes to prepare for reproduction. Puberty usually begins for women around age 10 or 11. After pubic hair begins to grow, the breasts will begin responding to hormonal changes in the body. Specifically, the production of two hormones, estrogen and progesterone, signal the development of the glandular breast tissue. This initial growth of the breast may be somewhat painful for some girls. During this time, fat and fibrous breast tissue becomes more elastic. The breast ducts begin to grow and this growth continues until menstruation begins (typically one to two years after breast development has begun). Menstruation prepares the breasts and ovaries for potential pregnancy.

Before puberty Early puberty Late puberty

the breast is flat except for the nipple that sticks out from the chest

the areola becomes a prominent bud; breasts begin to fill out

glandular tissue and fat increase in the breast, and areola becomes flat

Basic breast anatomy(http://www.007b.com/breast_anatomy.php)

The function of breasts is to produce milk for the baby.  Each breast has milk producing glands (also called lobules or alveoli) that make milk from the nutrients and water they take from the bloodstream.

Secondly, there are milk ducts that carry the milk to the nipple from the milk glands.   The system of milk glands and ducts resembles several bunches of grapes: the glands are the grapes, the ducts are the stems.  Like grapes come in bunches, the milk glands and ducts also are organized into several clusters that are called

The female breast.

lobes. The breast actually has 15-20 of these lobes or grape bunches in it.  From outside, the lobes feel like little nodes or lumps especially before menstruation.

The space in between the lobes is filled with connective and fatty tissue. Fat also surrounds the whole system of milk ducts and glands.  Usually the breasts of young women are mainly glandular tissue and that is why their breasts are firmer.  The softer the breasts are, the more fat they contain.

Note that the breast does not have any muscles (except for tiny ones in the nipples), so no amount of exercise will change their appearance.  The breast is supported by semi-elastic bands of tissue called Cooper's ligaments. These ligaments (along with the skin) stretch over time when the gravity pulls the breast down, and that is why the breast will start drooping or sagging.

The breast size and shape in different women varies a lot.  Some women have more glandular tissue in their breasts, some have less.  Some have more fatty tissue than others. Some have more connective tissue so their breasts are firmer, and yet some women are totally flat-chested.  The size and shape also varies over time in the same woman because of the changes during menstrual cycle, pregnancy, after weaning, and during menopause. Most of the size differences between women are due to the amount of fatty tissue in the breast.  But practically all breasts can make milk and help nurture the baby - and that is what makes breasts beautiful!

The rare exception to this is the so-called hypoplastic or underdeveloped breast that does not have much glandular tissue (or milk-making glands).  Hypoplastic breasts often are small, elongated or tubular shaped, narrow at the chest wall with wide space in between, and often have big areola.&nbps; Women with these tubular under-developed breasts may have low milk supply, but many of them can with the proper measures develop full supply and breastfeed succesfully.

MOST women's breasts are not totally symmetrical (don't judge by the models and actresses in the media since they have had theirs fixed, pushed up, padded and everything

else).  Usually, one breast is slightly larger or smaller, higher or lower, or shaped differently than the other.  It is kind of a similar situation to men's testes: usually the left one hangs lower than the other.

The darker part surrounding the nipple is called the areola. Areolas usually grow in size and get darker during pregnancy - as if making it easier for the baby to spot the place of nourishment. The little 'bumps' on the areola are called Montgomery glands, and they produce oil that lubricates the nipple/areola complex.

The nipple has several tiny openings in it through which the milk flows during lactation. Nipples can sometimes be flat, with a 'line' through them, or inverted, where the nipple is indented inward. Neither situation is serious or dangerous since the baby can usually pull the nipple out. By the way, a teenager nipple does not necessarily protrude but it is only truly flat nipple if it does NOT get erect when stimulated or when cold.

Nipples also come in all different kinds of looks.  Some women's nipples are constantly erect whereas some have nipples that only become erect when stimulated by cold or touch.  It is common to have some hair on the breast. The nipple can be flat, round, or cylindrical in shape.  The areola can be a very narrow ring, or may cover half of a small breast.  The color varies from pink to black.  Even so, these characteristics don't affect the breastfeeding process - with the exception that sometimes women with flat or inverted nipples have to use special measures to get the baby to feed. You can see pictures of nipples on our nipple gallery page, as well as links to web pages about flat/inverted nipples.

This medical illustration depicts a torso of a female figure showing normal breast anatomy. The pectoralis muscle, serratus muscle, and external oblique muscle, thoracic lymph nodes, (axillary lymph nodes, parasternal lymph nodes, subclavian lymphatic trunk, bronchomediastinal trunk), adipose glandular tissue and nipple are all included.

Anatomy of the breast. Ducts carry milk from the lobules to the nipple. The lobules and ducts are surrounded by fatty tissue and ligaments called stroma.

This medical illustration shows the network of lymph vessels and nodes located in the female axilla and breast region. It also demonstrates the mammary lobes and lactiferous ducts.

This stock medical exhibit features four views of the breast to describe the Progression of Breast Cancer. The following views are illustrated: 1- Normal anatomy of the breast 2- Early stage breast cancer with appearance of a small tumor mass. 3- Late stage breast cancer with growth and spread of the tumor mass. 4- Final image illustrating the spread of cancer through the lymph nodes.

emedicine

Breast Care

Anatomy Of The Breast

The breast consists of a mixture of:

Fat Milk glands - lobules that secrete milk during pregnancy

and breastfeeding Mammary ducts – canals that carry milk from the lobules

to the nipple openings Fibrous connective tissue Nerves Blood vessels

Lymph vessels – delicate vessels that collect lymph fluid from tissues and drain it back into the bloodstream

Small amounts of muscle tissue o In the nipple to allow it to become erect in response to sexual stimulation

or breastfeedingo Around the lobules to help squeeze milk into the ducts.o Key muscles support the breasts rom behind and underneath.

Breast size and shape is unique to each woman and is determined by heredity and body size. However, breast tissue changes throughout a woman’s lifetime depending on hormonal changes.

Breasts develop at puberty as hormones stimulate the system to form and enlarge lobules and ducts. Full development can occur any time between the ages of 12 and 19.

A woman’s monthly menstrual cycle causes breast granularity to change. Swelling and tenderness of both breasts may occur during the second half of the menstrual cycle. Cysts may grow and then shrink.

During pregnancy, the lobules multiply and begin to produce milk.

When a baby is born, milk is released into the ducts for breastfeeding (lactation). During menopause the number of lobules decreases and those remaining shrink. A

larger proportion of the breast is made up of fat so breast density decreases.